Download APRIL 2012 | PARK BRAKE LEVER

APRIL 2012 | PARK BRAKE LEVER LUBRICATION
The Skyjack boomlift models 40/45T, 61/66T, 46/51AJ, and telehandler models VR642,
VR843, ZB6042, and ZB8044 use drive axles with spring applied-hydraulically released parking
brakes. The parking brakes are actuated by a cylinder and dual lever mechanism on the top of
the axle housing. (Figures 1 & 2)
Park Brake Cylinder
(Rod end)
Quick release
mechanism
Support
Park Brake Lever arm
with grease fitting
Figure 1
Park Brake Cylinder
(Barrel End)
Park Brake Lever arm
with grease fitting
Figure 2
The park brakes are released when hydraulic pressure is applied to the brake cylinder and
the cylinder extends, pushing the brake levers apart. When hydraulic pressure is released, a
spring inside the brake cylinder retracts the rod, pulling the brake levers toward each other applying the park brake.
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APRIL 2012 | PARK BRAKE LEVER LUBRICATION
The park brake lever is equipped with a grease fitting and if not properly and regularly
lubricated, the lever can bind up on the support pivot, breaking apart the quick release
mechanism, causing the park brake to stay released.
Figure 3 shows the park brake cylinder quick release mechanism damaged because of a
seized brake lever support pivot.
Reduction
bushings and
detent
assembly
Park Brake
Cylinder
Circlip and washer
Support
Broken reduction
bushing
Figure 3
The pivot on the support seized and the pressure from the park brake cylinder pushed the
circlip off the brake actuator rod and cracked the reduction bushing. This broke the connection
to the park brake lever resulting in no parking brakes. It is very important to lubricate all of the
grease points on your equipment regularly and properly to avoid costly damage and equipment
downtime.
For more information regarding this axle, or any other component repair or maintenance,
please consult the correct service manual for the serial number of the unit you are working on.
If you have any questions regarding your Skyjack product, please call Skyjack Product
Support at 01691676236 or e-mail [email protected]
TECH TIDBIT
When maintaining or troubleshooting a liquid propane (L.P.) system, check the hose to
tank coupling for dirt or debris in the end. Also, check the tank fitting and the hose coupling for
the tank O ring. When removing an empty tank, the O ring can get stuck in the hose coupling
and prevent the coupling from threading fully onto the new tank’s fitting. The coupling looks
completely attached but the extra O ring will not allow the valve to extend far enough into the
tank fitting. It will not leak, but no L.P. will flow into the hose.
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